Unrecognized selector while removing all user posts from Firebase - swift

Question

I tried to delete all posts that belongs to specific user, however it crashes telling me error:
'-[FIRDataSnapshot removeValue]: unrecognized selector sent to
instance 0x174238c20'
but if I try to po the child, it prints out the child.
That is how I am doing it in Swift3:
FIRDatabase.database().reference().child("posts").queryEqual(toValue: self.currentUser.generalDetails.userName).ref.observe(.value, with: { (snapshot: FIRDataSnapshot!) in
for child in snapshot.children {
(child as AnyObject).removeValue() //This line gives the error.
}
})
That is the child that shold be removed if "username":"currentUser.generalDetails.userName":
posts
-KUaMd3YgJlQvv_P-kdK//This has to be deletod with all its children
content:
likes:
postId:
postImageStringUrl: close
profileImageUrl:
timestamp:
username:
Wha should cause the crash?
Edit: I updated code like this which says that I have to :
Consider adding ".indexOn": "posts/username" at / to your security
rules for better performance
however I have pretty ok security rules:
{
"rules": {
".read": "auth != null",
".write": "auth != null",
"Snuses": {
".indexOn": ["Brand", "posts/username"]
}
}
}
FIRDatabase.database().reference().queryOrdered(byChild: "posts/username").queryEqual(toValue: currentUser.generalDetails.userName)
.observeSingleEvent(of: .value, with: { snapshot in
if ( snapshot.value is NSNull ) {
print("not found")
} else {
for child in (snapshot.children) {
let element = child as! FIRDataSnapshot //the node data
let key = element.key //the key for the node
let nodeToRemove = FIRDatabase.database().reference().child(key)
nodeToRemove.removeValue()
}
}
})

Answer 1

I believe you are going to want to remove child by it's parent key, not the child.
Frank provided a short comment (which is actually THE answer) but here's a verbose example (Firebase 2.x but you'll get the idea):
ref.queryOrdered(byChild: "posts/username").queryEqual(toValue: "someUsername")
.observeSingleEvent(of: .value, with: { snapshot in
if ( snapshot?.value is NSNull ) {
print("not found")
} else {
for child in (snapshot?.children)! {
let element = child as! FDataSnapshot //the node data
let key = element.key! //the key for the node
let nodeToRemove = ref.child(byAppendingPath: key)
nodeToRemove?.removeValue()
}
}
})
something to look for is to make sure your paths are correct.
In the above code, 'key' is the parent node name like
-KUaMd3YgJlQvv_P-kdK
If you were to use
let ref = element.ref
it would be the specific path to that node, including the node name but no other data, like this
root_node/posts/-KUaMd3YgJlQvv_P-kdK
so the idea is once you have that reference, use use the reference to remove the node.
So if ref = root_node/posts/-KUaMd3YgJlQvv_P-kdK
then ref.remove(), it will remove that reference and the child data.

Answer 2

Although #Jay's answer does your job, but i was half way through already writing your answer, Give it a shot and let me know:-
let refe = FIRDatabase.database().reference().child("posts")
refe.queryOrdered(byChild: "username").queryEqual(toValue: currentUser.generalDetails.userName).observeSingleEvent(of: .value, with: { (snapshot) in
if let snapDict = snapshot.value as? [String:AnyObject]{
for each in snapDict {
print(each.key)
refe.child(each.key).removeValue(completionBlock: { (err, ref) in
print(ref)
})
}
}
}, withCancel: {(errO) in
})
It should delete every posts that the user made.. :)